CAPTAIN FANTASTIC
Well-Known Member
simple to operate not simple to dismantle
How much more reliable are 4t Outboards than 2t
- Thread starter jac
- Start date
simple to operate not simple to dismantle
DannyB
Well-Known Member
I stripped down a Johnston 10 HP twin two stroke when I was about 15/16 years old. Engine had been thrown out by the owner because it was seized and the dealer told him it was uneconomic to repair. First project of that type I'd done. I had to buy an impact driver to get the screws out of the leg because they were corroded in place, but apart from that it was simplicity itself. No manual, no experience, but I stripped it down to the last nut and bolt, ended up with the block with the two pistons stuck in it, put it in a bucket full of old engine oil, put a primus stove under it and heated it for a couple of hours. The pistons almost fell out. New piston rings, put it all back together, started second or third pull. I learned a lot from that engine, mainly how simple they are.
TQA
Well-Known Member
- Joined
- 20 Feb 2005
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- Carribbean currently Grenada
I am a cruising liveaboard in the Caribbean. I see hundreds of cruisers with OBs. For every 4T I see/hear I see 20+ 2T.
My 28 yr old Johnston 15hp started 3rd pull when cold and first pull after that. New plugs every year was all that was needed. It was stolen in St Barts, the thief passing up a brand new unsecured Honda 4T on the adjacent mooring to cut the security wire and steal my old Johnston.
No 4T for this old spanner monkey. My current OB is a Nissan [Tohatsu] 18 hp 2 stroke of course.
My 28 yr old Johnston 15hp started 3rd pull when cold and first pull after that. New plugs every year was all that was needed. It was stolen in St Barts, the thief passing up a brand new unsecured Honda 4T on the adjacent mooring to cut the security wire and steal my old Johnston.
No 4T for this old spanner monkey. My current OB is a Nissan [Tohatsu] 18 hp 2 stroke of course.
prv
Well-Known Member
That's not quite true, is it. You'll have a float and valve, throttle and choke butterflies, and a few linkage bits and bobs in the carb.
Still simpler than a 4-stroke, of course.
Is that so? Last I heard they were clamping down on non-Islander purchases, but that was a while ago. I know at least one person who'd be in the market for a new Tohatsu 2-stroke if available.
Pete
ip485
Well-Known Member
I too maybe just unlucky but purchased a new 9.9 hp 4 stroke yamaha. It was a nightmare. Left for any time and it often refused to start even with the engine run dry.
I gave up and pxed it for a 15hp 2 stroke. Just superb. Almost the same weight, has always started after a few pulls even after six months without use, and in use starts first or second pull.
Its a single experience but i would like 20 or 25 hp on the tender instead of the 15 and it will be a 2 stroke.
I gave up and pxed it for a 15hp 2 stroke. Just superb. Almost the same weight, has always started after a few pulls even after six months without use, and in use starts first or second pull.
Its a single experience but i would like 20 or 25 hp on the tender instead of the 15 and it will be a 2 stroke.
jac
Well-Known Member
Becoming convinced that I want to keep the 2t then - just buggered if I can work out why it won't start when it has brand new fuel in it (well 6 hours old now) from a garage that I know turns over a lot of fuel and I can see a spark from the brand new spark plug even in bright sunlight.
Next step I think will be adjusting the float valve as I have a feeling it may be flooding and then maybe try another spark plug in case this one is duff and I'm being to charitable to the state of the spark I can see.
Doesn't help in finding it very difficult to find decent manuals. Found one with great detail but seemed to suggest that the float valve didn't need to be tested/ adjusted on 2.5hp tohatsu s - just on the bigger engines. Fortunately the manuals on lakeys site have photos where the carb looks identical and thse have measurements so that's the next step I think!
Next step I think will be adjusting the float valve as I have a feeling it may be flooding and then maybe try another spark plug in case this one is duff and I'm being to charitable to the state of the spark I can see.
Doesn't help in finding it very difficult to find decent manuals. Found one with great detail but seemed to suggest that the float valve didn't need to be tested/ adjusted on 2.5hp tohatsu s - just on the bigger engines. Fortunately the manuals on lakeys site have photos where the carb looks identical and thse have measurements so that's the next step I think!
ex-Gladys
Well-Known Member
Removing the float chamber and clearing the needle valve is likely to solve your problems... I didn't really twig that you were seeing fuel on the water when trying to start. It's simple when you look at it ( can't remember exactly as it's a few years since I had a similar prob), and you may find a whole bunch of crud in the bottom of the float chamber. A spray of carb cleaner is your friend, spray over the rubber tip of the valve and the seat, and into the 'ole.
A very good 2stroke motorcycle engineer (Jack Nice who raced MZ's) once said to me about a standard bike, if it doesn't start within a few (2-3) kicks something's wrong with it. For outboards I extend that to 6 pulls before I take the plug out and check...
RichardS
N/A
Chuck a few drops of fuel (1/2 teaspoonish) in through the carb intake or even directly through the spark plug hole if you can see that the plug is completely dry. Ideally 2T fuel but it doesn't matter. If the engine then fires for a few seconds you know it's a carb problem and if it doesn't fire you know it's an ignition problem.
Richard
jac
Well-Known Member
Spark plug is wet - actually very wet - when I took it out after 8-10 pulls fuel dripped off it. Hence thinking it might be flooding as I can see a spark when I test it. That makes me think that either the spark is too weedy to ignite the petrol / air mix or there is too much fuel / not enough o2 for the spark to ignite.
RichardS
N/A
Yes. Sounds like flooding. Dry off the plug and heat up the end with a torch or put the whole thing in an oven and try again whilst it's just too hot to hold.
Richard
jac
Well-Known Member
So suspect it was flooding.
Stripped the carb and found the inlet needle and the bottom of the float bowl filled with white crystalline crud. ( IIRC varnishy crud is more brown in colour) jets all clear. Spark plug tester showed a nice light when pulling the string.
Have cleaned out the bowl and the inlet needle and reassembled - started 2nd pull. ( It did then stop quickly and refuse to start until I actually put some fuel into the tank but I can't really blame the engine for that)
Now jut wondering what the hell a white crystalline substance in the float bowl could be. The only thing I can think of is that somehow sea salt has got washed in there ?? SPray drying on the cowling then rain washing in ??? Maybe a salty mist through the carbs air intake??? Not so much clutching at straws as showing true desperation!!!
Tam Lin
Well-Known Member
Cocaine?
jac
Well-Known Member
No that's kept in the lifejackets.
ex-Gladys
Well-Known Member
Well done! Don't worry about what it is because it's taken 13 years for it to build up, just remember it as another possibility for a non-starter....
Lakesailor
Well-Known Member
If it makes you all feel better then believe that 2 strokes are better. I've had plenty of both and had more problems with 2Ts.
Don't forget to add to the moving parts the reed valve and the cranshaft seals.
How often have you heard of the extra moving parts on a 4T giving trouble? A simple camshaft, some valves and springs.
A lot of 4 T starting problems are to do with the different technique to turning them over. If you yank at it like a 2T it may be difficult to start.
The weight thing is also vastly overstated. It usually amount to 3 or 4 klos extra. Of course if you are struggling with the 2T the extra weight of the 4T will seem like a deal-breaker.
I have had a very excellent 3.5 Tohatsu (very old) and a very excellent 4hp Mariner in 2 strokes.
But I have had very excellent Mariner, Tohatsu and Yamahas in 4 stroke.
The Honda 5hp is the only one I wouldn't have again. More to do with vibration and poor running though.
jac
Well-Known Member
If it had taken 13 years to build up i'd be fine. That float bowl was cleaned with carb cleaner 3 times last year ( including winter lay up which may have been Jan this year!!) so the white crud built up in 3-6 months!
What is noticeable though is how easy it is to start now. as it emptys the bin fairly quickly ( it has cracked it) I only run for about 5 mins in the bin. Having got it idling nicely I stopped it and let it cool down ( although in 35 degrees temp that may be a misnomer) started again - first pull - no choke. left again for an hour - started first pull.
The other thing I noticed when I stripped it was the height of the float was off by almost 2mm ( 1mm v the 3mm mentioned in lakeys brilliant docs) Having been fettled by a pro last year ( including the carb) I had assumed it was adjusted correctly. Even last year when straight back from the shop it was a bit temperamental - tricky to start - needing juggling of choke and throttle to keep going until properly warm. Revs fluctuating when throttle opened. I'd put down to crud working through carb ( hence the 3 cleans) Looks like it was never properly adjusted by the "professional."
Using it to go to the Horse and Jockey at Curbridge on Saturday so will see how well it performs for real but looking so much better now. It's like it was several years ago!
Tam Lin
Well-Known Member
Sudden realisation, our council are going over to wheelie bins next year so I will be able to run my outboard at home!
ex-Gladys
Well-Known Member
Well, in that case vote with your feet and never use that engineer again...The more you learn about your own engine and how it works, the more confidence you will have in the engine....
dslittle
Well-Known Member
+1 for Mainbrayce. Good prices and friendly service. Just a happy customer.
jac
Well-Known Member
Have also been impressed by Maybrayce. Also having the 2.5hp Tohatsu I do regret not buying the 3.5 which is of course the same engine with bigger carb and a clutch neutral fitted! Have spent a lot on the boat this year so upgrading the tender OB is fairly low down the list - especially as it now works!